python · pablogsal · May 4, 2020 · May 2, 2020 · May 2, 2020
diff --git a/Grammar/python.gram b/Grammar/python.gram
@@ -245,6 +245,7 @@ star_etc[StarEtc*]:
    | '*' ',' b=param_maybe_default+ c=[kwds] {
        _PyPegen_star_etc(p, NULL, b, c) }
    | a=kwds { _PyPegen_star_etc(p, NULL, NULL, a) }
+    | invalid_star_etc

 kwds[arg_ty]: '**' a=param_no_default { a }

@@ -352,6 +353,7 @@ lambda_star_etc[StarEtc*]:
    | '*' ',' b=lambda_param_maybe_default+ c=[lambda_kwds] {
        _PyPegen_star_etc(p, NULL, b, c) }
    | a=lambda_kwds { _PyPegen_star_etc(p, NULL, NULL, a) }
+    | invalid_lambda_star_etc

 lambda_kwds[arg_ty]: '**' a=lambda_param_no_default { a }

@@ -632,6 +634,10 @@ invalid_comprehension:
 invalid_parameters:
    | param_no_default* (slash_with_default | param_with_default+) param_no_default {
        RAISE_SYNTAX_ERROR("non-default argument follows default argument") }
+invalid_star_etc:
+    | '*' (')' | ',' (')' | '**')) { RAISE_SYNTAX_ERROR("named arguments must follow bare *") }
+invalid_lambda_star_etc:
+    | '*' (':' | ',' (':' | '**')) { RAISE_SYNTAX_ERROR("named arguments must follow bare *") }
 invalid_double_type_comments:
    | TYPE_COMMENT NEWLINE TYPE_COMMENT NEWLINE INDENT {
        RAISE_SYNTAX_ERROR("Cannot have two type comments on def") }
diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
@@ -242,11 +242,11 @@ def baz():
        check('from __future__ import doesnt_exist', 1, 1)
        check('from __future__ import braces', 1, 1)
        check('x=1\nfrom __future__ import division', 2, 1)
+        check('def f(*):\n  pass', 1, 7 if support.use_old_parser() else 8)

    @support.skip_if_new_parser("Pegen column offsets might be different")
    def testSyntaxErrorOffsetCustom(self):
        self.check('for 1 in []: pass', 1, 5)
-        self.check('def f(*):\n  pass', 1, 7)
        self.check('[*x for x in xs]', 1, 2)
        self.check('def f():\n  x, y: int', 2, 3)
        self.check('(yield i) = 2', 1, 1)

diff --git a/Lib/test/test_peg_parser.py b/Lib/test/test_peg_parser.py
@@ -603,6 +603,12 @@ def f():
    ("1 += 1", "cannot assign to literal"),
    ("pass\n    pass", "unexpected indent"),
    ("def f():\npass", "expected an indented block"),
+    ("def f(*): pass", "named arguments must follow bare *"),
+    ("def f(*,): pass", "named arguments must follow bare *"),
+    ("def f(*, **a): pass", "named arguments must follow bare *"),
+    ("lambda *: pass", "named arguments must follow bare *"),
+    ("lambda *,: pass", "named arguments must follow bare *"),
+    ("lambda *, **a: pass", "named arguments must follow bare *"),
 ]

 GOOD_BUT_FAIL_TEST_CASES = [

diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
@@ -627,9 +627,9 @@
    Traceback (most recent call last):
    SyntaxError: cannot assign to __debug__

-    # >>> with (lambda *:0): pass
-    # Traceback (most recent call last):
-    # SyntaxError: named arguments must follow bare *
+    >>> with (lambda *:0): pass
+    Traceback (most recent call last):
+    SyntaxError: named arguments must follow bare *

 Corner-cases that used to crash: